CDC Offers Hope in Fighting Brain-Eating Ameba

June 23, 2015 by Blog AdministratorBy Sioux Henley Campbell

Photomicrograph depicting some of the histopathologic changes associated with an infection found in a brain tissue specimen due to the presence of free-living amoebae of the genus, Naegleria.

The investigational drug miltefosine (trade name, Impavido) has been successfully used to treat Naegleria fowleri.

Surviving a Brain-Eating Ameba

After swimming in a local waterpark, 12-year old Kali Hardig developed a high fever, headache, and nausea. When she worsened, her parents rushed Kali to Arkansas Children’s Hospital. Within 30 hours of becoming ill, doctors had diagnosed Kali with primary amoebic meningoencephalitis(PAM) caused by the free-living ameba Naegleria fowleri. Because it destroys brain cells, Naegleria fowleri has also been called a brain-eating ameba. Infections are nearly always fatal.

Doctors treated Kali with antibiotics and antifungals and aggressively managed her brain’s swelling–including cooling her body below normal body temperature. They consulted with CDC about the investigational drug miltefosine, found to help kill brain-eating amebas in the laboratory. CDC was able to rapidly supply miltefosine because of an agreement with FDA to keep the drug on site at CDC and ship by physician request.

After 22 days in intensive care that included a drug-induced coma, lowered body temperature, and multiple drugs–including miltefosine–Kali left the hospital. She’s since made a full recovery and returned to school. Kali is one of three Naegleria fowleri survivors in the U.S. in the past 35 years and the first since 1978.

Note : Kali’s mother, Traci Hardig, courageously battled stage four breast cancer for nine years, including during and after Kali’s own battle with the brain-eating ameba. Traci died on December 27, 2014.

Fighting Brain-Eating Ameba [i]

It sits in a blister pack, secured in a nondescript office at the Centers for Disease Control (CDC), just a few phone calls away from being flown to a patient’s bedside for emergency treatment. Miltefosine is one of several drugs used to treat rare[ii] diseases that the CDC Drug Service makes available to doctors licensed in the United States.

These special drugs are kept onsite and are acquired from the drug manufacturer, as needed. They have either limited commercial availability or are considered investigational and require special Food and Drug Administration (FDA) authorization for patient use.

A Four-Year Journey

Miltefosine is a drug used to treat leishmaniasis, a rare tropical parasitic disease[iii]. It’s also shown promise in treating free-living ameba (FLA)–a single-cell living organism commonly found in warm freshwater or soil. FLA infections are considered to be “low incidence but high impact”—meaning, they are rare but deadly. Because of this, miltefosine has its own pager number that physicians can access 24/7.

Since 2009, CDC has helped treating physicians get miltefosine from FDA on a patient-by-patient basis. Until recently, the only source of miltefosine was from Germany. The drug often took over a week to get to a hospital, frequently being held up in customs despite having proper approvals and paperwork.

In late 2011, difficulties in obtaining miltefosine in a timely manner prompted CDC to find ways to keep a supply of the drug at the agency for FLA infections. A CDC scientist drafted the required FDA-documentation that allows the use of investigational drugs for patients with serious or immediately life-threatening diseases who lack other treatment options.

Over the next two years, CDC gathered evidence to justify treatment of FLA infections with miltefosine. On May 24, 2013, CDC received the “safe to proceed letter” from FDA. After an urgent plea to rush the order to be available for “ameba season” (mid-to-late summer when amebas living in warm, stagnant water grow rapidly), miltefosine arrived at the agency.

The drug arrived just in time. Less than a week later, an Arkansas physician contacted CDC about a young patient named Kali that urgently needed miltefosine. Despite multiple hurdles, Kali received miltefosine approximately 36 hours after CDC was notified. (See Surviving a Brain-Eating Ameba to the right.) Today, Kali has fully recovered and is back at school.

On August 23, 2013, CDC announced an agreement with FDA to make miltefosine available directly from CDC to doctors treating FLA infections in the United States. It is available for treatment of free-living ameba (FLA) infections caused by Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba species. Clinicians can contact the CDC Emergency Operations Center at 770-488-7100 to consult with a CDC expert about obtaining this drug.

In 2014, CDC sent 14 shipments of miltefosine to doctors treating possible FLA infections. Miltefosine was approved by the FDA in 2014 to treat leishmaniasis. It remains under an investigational treatment program with FDA for FLA infections.

About the CDC Drug Service

CDC manages and distributes biologic agents and drugs that meet important medical needs and provide public health surveillance. Due to limited demand in this country, commercial use and/or licensure is neither practical nor profitable for many pharmaceutical companies.

The CDC Drug Service:

Maintains a formulary of investigational new drugs to distribute to requesting physicians licensed in the United States
- Drugs are subject to change based on current public health needs, updates to treatment guidelines, and/or drug availability
Collaborates with partners internal and external to CDC for drug releases, surveillance, and patient treatment.

References:

[i] About the Term “Ameba.” In U.S. English, the single-celled living organism described here is an ameba. The word amoeba, with an “o”, is used as part of a scientific genus name (such as Amoeba or Acanthamoeba). In British English, both the generic organism term and genera names are spelled amoeba with an “o”.

[ii] There is no universal definition of a “rare disease” but the U.S. Rare Disease Act of 2002 defined a rare disease as affecting less than 200,000 people in the U.S. and this definition has been adopted by the National Institutes of Health, Office of Rare Diseases.

[iii] The FDA approved miltefosine in 2014 to treat the rare tropical disease leishmaniasis and no longer considers it as investigational when used for this specific purpose.

June 23, 2015 by Blog Administrator